The moon & eBay

[rasputin]

I got this shot yesterday with my 100-300mm Minolta AF xi lens:



It's not a fantastic lens by any standards, but it does OK and cost me under £100 .

But - it got me thinking: My M42-mount Carl Zeiss 135mm f/3.5 lens is fantastic and ultra sharp wide open. IQ degrades only slightly when fitted with a 2x teleconverter I got for £3 on eBay.

But why limit it to one teleconverter?

I have just been on eBay and now on it's way to me is a 3x teleconverter, and possibly another 2x if my "best offer" is accepted. Under £20 for both.

And 135mm f/3.5 becomes 1620mm f/37

Will it work? (really should have asked before buying...)

[4hero]

f37? You'll be struggling with that ISO100, f9'ish, 1/1000 sec'ish to get something like this.



If you bring the shutter speed down the moon will be all blurry, it moves pretty damned fast.

Good luck though!

Edited by 4hero on Thursday 13th August 10:32

[Tycho]

I did this with a 300mm lens and 3 2x TC's. Finding the bloody moon was the first issue. Got about a 10th of the moon in the full frame and you could see the craters nicely but rather blurred.

[havoc]

4hero said:

f37? You'll be struggling with that ISO100, f9'ish, 1/1000 sec'ish to get something like this.
If you bring the shutter speed down the moon will be all blurry, it moves pretty damned fast.

So bring the ISO up. ISO-800 on a modern body isn't THAT grainy...

[rasputin]

Got my new teleconverters. So I now have two 2x and a 3x.

Now I just need to wait for a clear night in Scotland. Any year now...

[rasputin]

In the meantime I tested the sharpness of stacked teleconverters with a pile of coins.

CZ 135mm lens on its own:
Full Frame / 100% crop.
/

With 2x TC:
Full Frame / 100% crop.
/

With 3x TC:
Full Frame / 100% crop.
/

With 2x and 3x TCs:
Full Frame / 100% crop.
/

With two 2x and one 3x TCs:
Full Frame / 100% crop.
/

It was getting quite dark by the time I took the last one, so DOF (coins were 2 meters away) and focusing was a bit tricky.

All were taken at ISO 100. The last picture was a 30 second exposure and still too dark. But the 2x and 3x only needed 6 seconds in quite a dark room - and sharpness isn't too bad.
So with the ISO bumped up a bit, and with a bright moon, I think it should be do-able

[DIW35]

I'll be really inteested to see how you get on. Love taking photos of the moon.

[Famous Graham]

4hero said:

If you bring the shutter speed down the moon will be all blurry, it moves pretty damned fast.

About 12 seconds is the max you can go really, without tracking. If I remember correctly.

[DIW35]

Famous Graham said:

4hero said:

If you bring the shutter speed down the moon will be all blurry, it moves pretty damned fast.

About 12 seconds is the max you can go really, without tracking. If I remember correctly.

That's all dependent on the level of magnification you are using. The more you zoom in, the greater the apparent speed the moon is moving. I couldn't get away with more than a second or so with my telescope, which is the equivalent of 1600mm or so.

[cbcbcb]

DIW35 said:

Famous Graham said:

4hero said:

If you bring the shutter speed down the moon will be all blurry, it moves pretty damned fast.

About 12 seconds is the max you can go really, without tracking. If I remember correctly.

That's all dependent on the level of magnification you are using. The more you zoom in, the greater the apparent speed the moon is moving. I couldn't get away with more than a second or so with my telescope, which is the equivalent of 1600mm or so.

If you combined 30 1/2 second exposures with Photoshop by adding each frame together, you'd effectively get a 15 second exposure, and you could adjust the alignment of each frame to correct for the movement of the moon.

[DIW35]

cbcbcb said:

DIW35 said:

Famous Graham said:

4hero said:

If you bring the shutter speed down the moon will be all blurry, it moves pretty damned fast.

About 12 seconds is the max you can go really, without tracking. If I remember correctly.

That's all dependent on the level of magnification you are using. The more you zoom in, the greater the apparent speed the moon is moving. I couldn't get away with more than a second or so with my telescope, which is the equivalent of 1600mm or so.

If you combined 30 1/2 second exposures with Photoshop by adding each frame together, you'd effectively get a 15 second exposure, and you could adjust the alignment of each frame to correct for the movement of the moon.

That's a useful technique for seep space objects, where it often takes several minutes of exposure to get anything worthwhile, but it's usually not necessary for images of the moon.

There are also programs available that will register and stack several photographs, as well as processing and applying dark, flat and bias images to maximise any data that you have managed to capture.

[Famous Graham]

DIW35 said:

Famous Graham said:

4hero said:

If you bring the shutter speed down the moon will be all blurry, it moves pretty damned fast.

About 12 seconds is the max you can go really, without tracking. If I remember correctly.

That's all dependent on the level of magnification you are using. The more you zoom in, the greater the apparent speed the moon is moving. I couldn't get away with more than a second or so with my telescope, which is the equivalent of 1600mm or so.

Hang on, the moon's obviously moving at a fixed rate - if you took a photo with a 50mm and a 400mm, and had a resolution high enough to zoom the 50mm's image to the same "size" (ie size of the moon on the screen or paper) as the 400mm, they'd be the same, all other things being equal.

Wouldn't they?

[SamHH]

Famous Graham said:

Hang on, the moon's obviously moving at a fixed rate - if you took a photo with a 50mm and a 400mm, and had a resolution high enough to zoom the 50mm's image to the same "size" (ie size of the moon on the screen or paper) as the 400mm, they'd be the same, all other things being equal.

Wouldn't they?

I think they would, but then your camera doesn't grow more pixels when you fit a shorter focal length lens, so it wouldn't make a difference in practice.